A THAAD interceptor successfully makes contact with its target during a test in the night sky. (Photo: U.S. Missile Defense Agency)
Ballistic missile defense (BMD) is suddenly topical again. It tends to become prominent in the news every few decades, as in the 1970s, when the Anti-Ballistic Missile (ABM) treaty—a component of the larger SALT I treaty between the United States and the Soviet Union—put severe limitations on BMD development.
In the 1980s when Ronald Reagan proffered grandiose ideas of futuristic and comprehensive defense systems that went nowhere; and in the 2000s, when the George W. Bush administration scrapped the ABM treaty and pushed for rapid BMD development. It caught the public’s imagination, in particular, during the Persian Gulf War (1991), owing to exaggerated claims concerning the effectiveness of the Patriot missile system in defending U.S. troops in Saudi Arabia from Iraqi missile attacks.
The current tensions between North Korea and the United States, and North Korea’s advances in offensive missile technology, have understandably renewed interest in the country’s capacity to defend against missile attacks. Apparently, people have also been concerned by reports that the new South Korean administration—that of Moon Jae-in, inaugurated in May of this year—is not a fan of the THAAD system that President Obama and Moon’s predecessor agreed to deploy in South Korea.
I heard a caller on a radio program register concern that Moon’s refusal to deploy the system (if it came to that) could undermine the defense of the United States against a North Korean missile attack. While there are many things to be concerned about, that is actually not one of them.
Terminal High-Altitude Area Defense
The system mentioned by the caller is the U.S. Army’s Terminal High-Altitude Area Defense (THAAD), and it has now been deployed in South Korea (as well as in Guam). The reason that it is unrelated to that particular caller’s concerns is that this is a deployment intended to defend South Korea from attacks by North Korea. It is designed to defend a larger area than the older Patriot system (and its development took the experiences of the Gulf War into account), but it is still designed to defend the area around itself against short- or medium-range missiles.
It does so by slamming into the warhead hurtling toward it during the terminal phase of that warhead’s trajectory (THAAD destroys its target by force of impact; it has no explosive charge.) THAAD is not designed to counter an intercontinental ballistic missile (ICBM) or any missile targeted against a distant country (as in defending the United States from a position in South Korea).
THAAD is a new system and has never been used in combat, so we must be cautious about making claims concerning its effectiveness in combat conditions. The good news (especially for South Korea and Guam) is that in tests performed by the Pentagon’s Missile Defense Agency (MDA), THAAD was reported to have performed successfully in 14 out of 14 tests. Furthermore, in its most recent test, No. 14 in July 2017, THAAD successfully countered an intermediate-range ballistic missile (IRBM), the sort that North Korea would need in order to reach Guam.*
Ground-Based Midcourse Defense
That said, the defense of the United States has not been completely forgotten, it merely involves a different system. This is the Ground-Based Midcourse Defense (GMD); a total of 32 interceptors are deployed in Alaska with four additional interceptors in California. Like THAAD, GMD destroys its target by means of kinetic energy, slamming into it at extraordinarily high speeds (10 kilometers per second, or more than 22,000 miles per hour). Unlike THAAD, it is designed to strike its target, an ICBM, during the middle portion of its trajectory, when the warhead is actually outside the Earth’s atmosphere. (GMD’s nonexplosive warhead is actually called an “exoatmospheric kill vehicle,” or EKV).
The Less-Good News
The less-good news is that GMD’s record is not the same as THAAD’s. Like THAAD, it has never been employed in combat. In terms of testing, only 10 out of 18 tests have been considered successful. Nor has its performance been improving noticeably. Since 2008, its record is two out of four. Moreover, critics consider most of the testing to have be highly unrealistic. For example, no test has involved the use of decoys or other cheap countermeasures.** The GMD’s first ever test against an ICBM-class missile came only this year, although it was successful.
Part of GMD’s problem is that it is simply harder to shoot down an ICBM in space. Some physicists question the effectiveness of the whole concept. The other part of the problem may be GMD’s unique development history. Back in 1995, a National Intelligence Estimate assessed that countries like Iran and North Korea were unlikely to develop a working ICBM in the next 10 years. Republicans in Congress, without any evidence, treated this assessment as an insult and an obvious example of a Democratic administration politically manipulating intelligence to get a preferred outcome.
Congress established the Commission to Assess the Ballistic Missile Threat to the United States, under former secretary of defense Donald Rumsfeld. The Rumsfeld Commission reported in 1998 that North Korea or Iran could develop an ICBM in as little as five years, with enough foreign help. (Needless to say, North Korea is developing ICBM’s only now, 22 years after the original NIE, and Iran has yet to do so.)
In 2001, George W. Bush was inaugurated as president and Donald Rumsfeld once again became secretary of defense. (Among new defense secretaries, he was both the youngest—in the 1970s—and the oldest—in the 2000s—in history.) One of his top priorities was the immediate development of the Ground-Based Midcourse Defense. Since he considered the system’s deployment so urgent, the Pentagon opted to develop and deploy simultaneously. The first interceptor was deployed in 2004, at a time when its most recent test had been a failure and its booster was already slated for replacement. Both deployment and development continue to this day. The cost to date has been about $40 billion, and they are still trying to work out the bugs.
In 2014 the Pentagon announced plans to develop a redesigned kill vehicle (RKV) by 2020, which would—hopefully—be more reliable and cost effective. Meanwhile, military leaders have questioned whether the current missile defense model is sustainable and have begun to explore entirely new concepts for defending against missiles, some of which have been considered and rejected before. At the same time, the Pentagon has resisted pressure from Congress to deploy additional GMD interceptors along the East Coast, arguing that better sensors and better interceptors are needed before expansion to new sites can be considered.
More Time?
It is possible, however, that we may have a bit more time than we think. Although North Korea reportedly tested its first two ICBMs in July, some observers now doubt whether the missiles were fully as advertised. It appears that the dummy warheads may have been much lighter than real ones would have been, artificially extending the missiles’ range during the tests.
Analysts also disagree as to whether the North Koreans are ready to fit a warhead into a missile and whether they have a reentry vehicle capable of sustaining the heat and pressure of returning from space through the atmosphere. We could certainly use the extra time.
Meanwhile, if the North Koreans should develop an ICBM and use it (which is not preordained), we can always shoot two or three interceptors at it in the hope of hitting it with at least one. Of course, no one has tested to see if that works.
*Other systems designed for tactical or theater defense include improved versions of the Patriot missile and the ship-borne Aegis system, a land-based version of which is being deployed in Europe.
**Defenders of the GMD system sometimes assert that a country with a relatively low level of technological development, such as North Korea, could not produce effective decoys. It seems fairly clear, however, that any country that can produce an ICBM is probably sophisticated enough to produce decoys. In fact, any country capable of producing Mylar party balloons may be able to produce effective decoys. There is no resistance in outer space, and a balloon will fly much like a warhead.
